Drawing steel tubes.



M. DERIHON.

DRAWING STEEL TUBES.

AFFLiCATION FILED 001.23. 1915.

1,187,275. Patented June 13, 1916.

a d N I l /6 w v WITNESSES INVENTORZZarZaZfiraZon MARTIN DERIHON, OF LONCIN-LEZ-LIEGE, BELGIUM.

DRAWING STEEL TUBES.

Specification of Letters Patent.

Patented June 13, 1916.

Application filed October 23, 1915. Serial No. 57,571.

To all whom "it may concern Be it known that I, MARTIN DERIHON, a subject of the King of Belgium, residing at Loncin-lez-Liege, Belgium, have invented certain new and useful Improvements in Drawing Steel Tubes, of which the following is a specification.

The present invention relates to a method of drawing steel tubes, particularly thin tubes having a large coeflicient resistance. The employment, in connection with these kind of tubes, of the known drawing processes only permits of obtaining a slow and progressive thinning of the tube, which necessitates a large number of passes and renders the process slow and costly. On the other hand the attempts at hot drawing have roved fruitless owing to the difliculty of bringing the tubes to and maintaining them at the necessary high temperature, especially at the point where the drawing takes place and without causing an inadmissible heating of the die and mandrel.

The desired result is obtained, according to the present invention, by means of an electric current (continuous or alternating) passing from the die or mandrel (or other conductor) through the portion or crosssectional areaof the tube to be drawn which is situated between these two parts. The resistance offered to the passage of the current by the surfapes in contact gives the desired high temperaturefwithout necessitating any preliminary heating of the tube, immediately it has passed through the die.

The accompanying drawing shows diagrammatically the arrangement for carrying out the process.

a shows the die in longitudinal section; b the mandrel provided with a shank 0; d the steel tube, partly drawn to the desired dimensions.

. pp y 2 which cools The electric circuit includes the source of the conductors e, the die a, the walls of the tube d, and the mandrel b, with its shank 0. The current may be continuous or alternating and is preferably of a low voltage, but of great intensity. The current can, also pass from the die a to the tube d and from the latter directly to the dynamo f; also the local heating of the tube can be obtained by induced currents.

Having fully described my invention, what I claim and desire to secure by Letters Patent is 1. A method of drawing seamless steel tubes consisting in passing the tube between a stationary outer die and a substantially stationary inner mandrel so as to extend the tube and externally reduce the thickness of the walls, and in passing an electric current uniformly between the entire circumference of the mandrel and the outer die so as to uniformly traverse the walls of the tube between the said die and mandrel and thereby heat the tube over the whole cross-sectional area in the region where the drawing takes place.

2. A method of drawing tubes consisting in passing the tube between a die and mandrel to reduce the thickness of the walls of the tube, and in passing an electric current through the whole cross-sectional area of the tube in the region where the drawing takes place.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

MARTIN DERIHON.

Witnesses:

F. STRUoKHoFn, JAMES E. REILLY. 

